Cleaning and liquid contact with solids – Processes – Including regeneration – purification – recovery or separation...
Patent
1997-08-12
1999-03-02
El-Arini, Zeinab
Cleaning and liquid contact with solids
Processes
Including regeneration, purification, recovery or separation...
134 2, 134 10, 134 26, 134 40, B08B 308, B08B 304
Patent
active
058765107
DESCRIPTION:
BRIEF SUMMARY
This is a national stage application of PCT/US96/02900 filed Mar. 4, 1996.
The process of the present invention relates to a process for cleaning one or more articles.
FIELD OF THE INVENTION
In many industrial processes articles have to be cleaned, either during finishing or prior to further processing, in order to remove impurities like grease, salts or other water-soluble or water-insoluble impurities from the articles. For example, articles with hard surfaces, such as glass, metallic or polymeric surfaces, often undergo one or more cleaning operations during production, finishing or recycling processes. Organic solvents are frequently used due to their excellent cleaning capability and fast evaporation rate. Depending on the type of organic solvent, it is advisable to take precautions to minimize the release of the organic solvent to the environment. Aqueous cleaning compositions are also known. The main component of aqueous cleaning compositions is water which is mixed with active ingredients, such as bases or acids, surfactants, builders, in some cases a minor amount of one or more organic solvents and small amounts of optional additives. One disadvantage of these aqueous compositions is their usually long evaporation time. Another disadvantage is that such aqueous compositions often leave residues on the article, which is not acceptable if high purity of the article is required. Therefore, in the metal working industry, in the optical industry or in other industries it is common to rinse articles with water of high purity after the last cleaning step if the articles have been cleaned with an aqueous cleaning composition and if high purity of the articles is required. Unfortunately, the evaporation rate of water alone is very low. Either the articles dry very slowly or much energy is required for forced drying of the articles if the drying time is to be reduced.
DESCRIPTION OF THE PRIOR ART
U.S. Pat. No. 5,271,773 discloses a process for cleaning articles with an aqueous solution of terpene. The aqueous solution of terpene is said to effectively clean water-insoluble contaminants, and upon settling, to quickly release contaminants from the wash solution. The articles contaminated with water-insoluble materials are cleaned as follows: (a) they are contacted with an aqueous solution comprising 1.86 to 37.2 volume percent of a terpene and 0.14 to 2.8 volume percent of a surfactant, (b) removed contaminants are allowed to separate from the aqueous solution and (c) the terpene is separated from water which may then be used to rinse the articles. The U.S. Patent teaches that the separated aqueous solution which comprises terpene, surfactant and some residual amounts of contaminant can be directly recycled to clean the articles. However, high purity cannot be achieved with this method. Alternatively, the aqueous composition can be subjected to a filtration for separating terpene and surfactant. Unfortunately, in many applications the purity of the recovered water is still not sufficient for rinsing the cleaned articles.
Accordingly, one object of the present invention is to provide a process for cleaning one or more articles by which high purity of the articles is achieved. A preferred object of the present invention is to provide an efficient cleaning process which does not make use of a substantial amount of halogenated solvents.
SUMMARY OF THE INVENTION
One aspect of the present invention is a process for cleaning one or more articles which comprises the steps of: total weight of a) and b), features of: from 99.99 to 60 weight percent of water and from 0.01 to 40 weight percent of said organic solvent, based on the total weight of the rinsing agent, whereby the water content in the rinsing agent is higher than the water content in the cleaning agent, at least a portion of the rinsing agent used in step II) and subjecting the combined liquid to an azeotropic distillation, separating the azeotrope into a water-rich phase and a solvent-rich phase and recycling at least a portion of the solvent-rich
REFERENCES:
patent: 3982325 (1976-09-01), Sigl et al.
patent: 5271773 (1993-12-01), Hamilton et al.
patent: 5300154 (1994-04-01), Ferber et al.
Derwent Abstract, "Dewatering Porous Glass--by Introducing Water Immiscible Solvent to From Azeotropic Vapour Mixture," JP 61127632; Japan.
Derwent Abstract, Detergent Composition for Degreasing--Comprises Propylene Glycol-Based Solvent, e.g. Propylene Glycol Mono-n-Butyl Ether, and Water, JP 6146041; Japan.
Kuemin Marius A. M.
Schneider Michael
El-Arini Zeinab
The Dow Chemical Company
LandOfFree
Process for cleaning articles does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for cleaning articles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for cleaning articles will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-418371